VoIP Signaling and Transport
VoIP transport consists of a stream of VoIP packets.
Each VoIP packet contains a short amount codec-encoded voice.
There is no time to wait for error correction, so UDP is used.
The Real Time Protocol (RTP) header “fixes” weaknesses of UDP.
First, the RTP has a sequence number to place packets in order.
Second, RTP has a time stamp so that the voice steam
can be played back at the correct time.